The present invention relates to a connecting member for a fast-fit safety coupling for fluidtight connection of two pressurized-operating-fluid, in particular compressed-air orxe2x80x94gas, conduits.
Known fast-fit non-safety couplings substantially comprise a normally substantially cylindrical connecting member connected to a first of the conduits; and a normally substantially cylindrical endpiece connected to a second of the conduits and which fits releasably into an engaged position inside the connecting member.
The connecting member comprises a hollow main member connected to the first conduit; a slide valve member fitted to slide axially inside the main member; a cylindrical helical spring interposed between the main member and the valve member, and which exerts axial pressure on the valve member to keep it in a first work position isolating the first conduit in fluidtight manner from the outside; and releasable stop means for retaining the endpiece of the connecting member in the engaged position, wherein the endpiece exerts opposite pressure on the valve member to overcome the pressure of the spring and so keep the valve member in a second work position permitting fluid flow between the first and second conduit.
A drawback of such couplings is that, when disconnected, the endpiece, pushed by the pressure of the fluid and the return pressure of the spring, tends to be released violently from the connecting member and possibly strike and, at times, injure the operator, or at least damage any nearby machinery or other objects.
To eliminate the above drawback, fast-fit safety couplings have been devised, as described, for example, in international Patent Application n. WO99/19657 filed by the present Applicant, and wherein the main member of the connecting member comprises axially spaced first and second releasable stop means. More specifically, the first stop means cooperate with the endpiece to lock it in the engaged position; and the second stop means cooperate with the endpiece to keep it, upon release of the first stop means and when disconnected from the connecting member, in a withdrawn safety position, wherein the endpiece is mechanically connected to the main member, and the valve member is set to the first work position isolating the first conduit in fluidtight manner and wherein the operating fluid inside the coupling, between the first and second conduit, is allowed to flow out.
The first stop means are interposed between the main member and the valve member, and the second stop means comprise releasable retaining means carried by the valve member and which cooperate with the endpiece to make it integral with the valve member as the endpiece moves between the withdrawn safety position and the forward engaged position.
More specifically, the second stop means comprise a selection ring nut, which is carried by the valve member, is normally maintained by a spring in a predetermined axial position on the valve member, and can be pushed axiallyxe2x80x94in opposition to the spring and in the opposite direction to that in which the valve member moves from the second to the first work positionxe2x80x94to release the retaining means.
Though in many respects extremely advantageous and safe, the above solution still leaves room for improvement.
In particular, in the event the user, when releasing the first stop means and so moving the valve member from the second to the first work position, inadvertently grips and prevents the selection ring nut from moving integrally with the valve member, the retaining means may be released simultaneously, thus resulting in violent release of the endpiece from the connecting member. Axially retaining the selection ring nut with respect to the valve member, in fact, results in relative movement of the selection ring nut with respect to the valve member in the retaining means release direction.
It is an object of the present invention to provide a connecting member for a fast-fit safety coupling, designed to eliminate the above drawback typically associated with the aforementioned known safety couplings.
According to the present invention, there is provided a connecting member for a fast-fit safety coupling, as claimed in claim 1.